global $wpdb;
$result = count_users();
$users = $result['total_users'];

for($id = 1;$id<$users;$id++){
    $result = $wpdb->get_results("SELECT wp_users.ID, wp_users.display_name, COUNT(wp_posts.post_author) AS 'Number_of_posts'
        FROM wp_users INNER JOIN wp_posts ON wp_users.ID = wp_posts.post_author
        WHERE wp_posts.post_type = 'post'
        AND wp_users.ID = $id", ARRAY_A);
}